HVAC lines

Bailey

Not-quite-so-new-guy
Sep 3, 2024
24
9
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I have two vacuum lines coming out of hvac box that I need some help figuring out where they run to. One looks like a purple color and the other is a gray color. Thank you
 
One should be defrost. GM defaults to defrost in event of failure. This is done because keeps windshield clear if HVAC fails. I think other is source to the switch. Source should come from vacuum ball after check valve, but I'll have to check.

What year??
 
One should be defrost. GM defaults to defrost in event of failure. This is done because keeps windshield clear if HVAC fails. I think other is source to the switch. Source should come from vacuum ball after check valve, but I'll have to check.

What year??
1980
 
This diagram showing black, I was thinking pink tracer for the defrost but you got purple and grey.
 

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Ok .. following from El Camino Central 2012 post on the 1982 El Camino, same question as yours.

Purple goes to the Vacuum Ball

Grey to the outside heater control valve. This will be an in line valve in the heater hose. Opens by vacuum, allows hot coolant to flow into the heater core.


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It's ok. My knee was hurting so soaking in tub with Epson salt, gives me something to do.

But, your right.
 
I have a sticky thread on this.

Took FOREVER to find, used to be a sticky in How To....
 
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